import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static HashSet<Character> special = null;
    static int minimumNumber(int n, String password) {
        // Return the minimum number of characters to make the password strong
        boolean capLetter = false;
        boolean smallLetter = false;
        boolean sp = false;
        boolean dig = false;
        
        for(int i=0; i<n; i++){
            char c = password.charAt(i);
            if(c>='A' && c<= 'Z'){
                capLetter = true;
            }
            else if(c>='a' && c<='z'){
                smallLetter = true;
            }
            else if(c>='0' && c<='9'){
                dig = true;
            }
            else if(isSpecialChar(c)){
                sp = true;
            }
        }
        
        int count = 0;
        if(!capLetter)
            count++;
        if(!smallLetter)
            count++;
        if(!sp)
            count++;
        if(!dig)
            count++;
        
        return Math.max(count, 6-n);
    }
    
    public static boolean isSpecialChar(char c){
        if(special == null){
            char[] arr = {'!','@', '#', '$', '%', '^', '&', '*', '(', ')', '-', '+'};
            special = new HashSet<Character>();
            for(char ch: arr){
                special.add(ch);
            }
        }
        
        return special.contains(c);
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        String password = in.next();
        int answer = minimumNumber(n, password);
        System.out.println(answer);
        in.close();
    }
}